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United States Patent | 5,583,651 |
De With ,   et al. | December 10, 1996 |
Video images are encoded by transform coding, resulting in data blocks each including a DC-coefficient and a plurality of AC-coefficients. The coefficients of a number of said transform blocks are variable-length encoded and transmitted. In order to avoid a complete loss of datablocks in case of a transmission error, the most significant codewords of a group of blocks are transmitted first so as to achieve that at least the DC-level of the blocks is likely to be retained. The coefficients may also be recorded on a videorecorder. Fast playback of recorded images so encoded, leads to very poor quality because some data blocks are not being read in the search mode. To improve this quality the DC-coefficients and if desired predetermined AC-coefficients of selected ones of the transform blocks to be recorded on one track are packed together to form a DC-packet and such packet is recorded on a selected part of the track. The DC-packet is chosen such that it can be read out as a unit at various search speeds, and can be read partially at higher search speeds.
Inventors: | De With; Peter H. N. (Eindhoven, NL); Nijssen; Stephanus J. J. (Eindhoven, NL); Rijckaert; Albert M. A. (Eindhoven, NL); Keesman; Gerrit J. (Eindhoven, NL) |
Assignee: | U.S. Philips Corporation (New York, NY) |
Appl. No.: | 601270 |
Filed: | February 14, 1996 |
Jan 13, 1992[EP] | 92200069 | |
Dec 14, 1992[EP] | 92203883 |
Current U.S. Class: | 386/68 |
Intern'l Class: | H04N 005/76; H04N 005/783 |
Field of Search: | 358/335,342,312,310 360/48,32,10.1,35.1 348/384,409,415 |
4907101 | Mar., 1990 | Keesen et al. | 360/48. |
5023710 | Jun., 1991 | Kondo et al. | 358/133. |
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5136391 | Aug., 1992 | Minami | 358/310. |
5196933 | Mar., 1993 | Henot | 358/133. |
5291282 | Mar., 1994 | Nakagawa et al. | 348/384. |
5337194 | Aug., 1994 | Wilkinson | 358/310. |
Foreign Patent Documents | |||
0448491 | Sep., 1991 | FR. | |
9102430 | Feb., 1991 | WO. |